From: Bart Van Assche <Bart.VanAssche@sandisk.com>
To: "bigeasy@linutronix.de" <bigeasy@linutronix.de>
Cc: "tglx@linutronix.de" <tglx@linutronix.de>,
"torvalds@linux-foundation.org" <torvalds@linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"mingo@kernel.org" <mingo@kernel.org>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"hpa@zytor.com" <hpa@zytor.com>
Subject: Re: [PATCH] cpu/hotplug: Serialize callback invocations proper
Date: Tue, 14 Mar 2017 17:38:00 +0000 [thread overview]
Message-ID: <1489513067.2676.9.camel@sandisk.com> (raw)
In-Reply-To: <20170314150645.g4tdyoszlcbajmna@linutronix.de>
On Tue, 2017-03-14 at 16:06 +0100, Sebastian Andrzej Siewior wrote:
> The setup/remove_state/instance() functions in the hotplug core code are
> serialized against concurrent CPU hotplug, but unfortunately not serialized
> against themself.
>
> As a consequence a concurrent invocation of these function results in
> corruption of the callback machinery because two instances try to invoke
> callbacks on remote cpus at the same time. This results in missing callback
> invocations and initiator threads waiting forever on the completion.
>
> The obvious solution to replace get_cpu_online() with cpu_hotplug_begin()
> is not possible because at least one callsite calls into these functions
> from a get_online_cpu() locked region.
>
> Extend the protection scope of the cpuhp_state_mutex from solely protecting
> the state arrays to cover the callback invocation machinery as well.
>
> Reported-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
> Fixes: 5b7aa87e0482 ("cpu/hotplug: Implement setup/removal interface")
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
So this regression was introduced in kernel v4.6? Anyway, thanks for the patch!
Bart.
next prev parent reply other threads:[~2017-03-14 17:38 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-03 17:37 [GIT pull] CPU hotplug updates for 4.9 Thomas Gleixner
2017-03-07 1:52 ` Bart Van Assche
2017-03-07 9:30 ` Thomas Gleixner
2017-03-07 22:32 ` Bart Van Assche
2017-03-08 8:25 ` Thomas Gleixner
2017-03-08 19:32 ` Bart Van Assche
2017-03-09 10:22 ` Thomas Gleixner
2017-03-09 17:20 ` Bart Van Assche
2017-03-09 17:43 ` Thomas Gleixner
2017-03-09 22:48 ` Bart Van Assche
2017-03-10 7:23 ` Ingo Molnar
2017-03-10 17:37 ` Bart Van Assche
2017-03-10 21:32 ` Bart Van Assche
2017-03-14 15:06 ` [PATCH] cpu/hotplug: Serialize callback invocations proper Sebastian Andrzej Siewior
2017-03-14 17:38 ` Bart Van Assche [this message]
2017-03-14 17:43 ` Thomas Gleixner
2017-03-14 18:25 ` [tip:smp/urgent] " tip-bot for Sebastian Andrzej Siewior
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